Timing Belts Catalogue

Calculation Parameters143Calculation ParametersII.Where the torque is knownClimbing resistance F inclThe name plate on motor gear boxesoften gives information about the torqueT. If this torque is given as the nominaltorque, the maximum torque while startingthe engine is calculated as follows:F incl= m * g * sin a [N]The total force to be transmitted by the timing belt is:F = (m * (a + g * sin a + g * cos a * (m oder ƒ ))) R * (1,05 ÷ 1,15) [N]T mech= T mot * (1,5 ÷ 2,5) [Nm]Result step 1:Leistung P mechoder Drehmoment T oder Kraft FIII. Where the mechanical forces areknown / can be calculatedMass inertial forces Fac when accelerating,forces from motion resistance Fremand climbing resistance Fincl have to betaken into account. Forces due to a largerotating mass (gear wheels, mandrels,clutches etc.) are considered a factorbetween 1.05 and 1.15:F = (F ac+ F rem+ F incl) * (1,05 ÷ 1,15) [N]The individual forces are determined asfollows:Acceleration force:F ac= m * a [N]with m...Mass to be accelerated, [kg]a...Maximum acceleration [m/s2]Step b: Select „Torque“, moulded, jointed or open lengthmaterialThe following calculation enables the selection of type oftiming belt needed. For example, open length material, jointed,moulded or truly endlessly („Torque“) timing belts:• Open length material is used almost exclusively in lineardrives. It can be supplied in every possible length (in generalup to 120 metres)• Moulded belts are inexpensive and have short lead times.The tensional strength is 20% less than open length orTorque type belts. The moulded sizes are only available incertain lengths (see appropriate AB catalogue for mouldedtiming belts sizes available). They are normally used for powertransmission applications, with centre-centre distances ofgenerally less than one metre.• Jointed timing belts are less expensive than Torque belts.Starting from the minimum, these can be made at any lengthrequested. They are available on short lead times, but due towelded joint the tensile strength is around 50% lower thanopen length or Torque belts. This weakness can be compensatedby using wider widths. This type of belt is mainly usedfor transportation and conveying purposes.Calculation ParametersMotion resistance:F rem= m * a * m *cos a bzw.F rem= m * a * ƒ R *cos a [N]with m...Moved mass [kg]g...Acceleration of gravity [m/s 2 ],9,81 m/s 2a... Angle of gradient [°]m... Coefficient of friction [-],approx. 0,1... 0,4f R... Coefficient of rolling friction [-],approx. 0,01 ... 0,05• Torque timing belts are the most efficient due to the trulyendless nature of the product. Torque belts are highest pricedand depending on the number of teeth are generally madeto order. They are used for high performance drives as wellas for heavy load transportation applications.Result step 2: Open length material, jointed,moulded or Torque beltCopyright © Ammeraal Beltech 2006